Re: [PATCH v8 09/14] PCI: tegra194: Allow system suspend when the Endpoint link is not up

[Manikanta Maddireddy <mmaddireddy@nvidia.com>]

On 09/04/26 2:33 am, Bjorn Helgaas wrote:
> On Wed, Apr 08, 2026 at 03:59:59PM -0500, Bjorn Helgaas wrote:
>> On Wed, Mar 25, 2026 at 12:37:50AM +0530, Manikanta Maddireddy wrote:
>>> From: Vidya Sagar <vidyas@nvidia.com>
>>>
>>> Host software initiates the L2 sequence. PCIe link is kept in L2 state
>>> during suspend. If Endpoint mode is enabled and the link is up, the
>>> software cannot proceed with suspend. However, when the PCIe Endpoint
>>> driver is probed, but the PCIe link is not up, Tegra can go into suspend
>>> state. So, allow system to suspend in this case.
>>
>>> +static int tegra_pcie_dw_suspend(struct device *dev)
>>>   {
>>>   	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
>>> -	u32 val;
>>>   
>>>   	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
>>> -		dev_err(dev, "Failed to Suspend as Tegra PCIe is in EP mode\n"); > -		return -EPERM;
>>> +		if (pcie->ep_state == EP_STATE_ENABLED) {
>>> +			dev_err(dev, "Tegra PCIe is in EP mode, suspend not allowed\n");
>>
>> Should this message say something about endpoint suspend not being
>> allowed because the link is up?  IIUC, the endpoint *can* suspend if
>> the link is down.
> 
> Oh, and I forgot: the subject line says "allow *system* suspend", but
> it looks like this patch is concerned with *endpoint* suspend.
> 
> I assume that whatever an endpoint does, it can't prevent the host
> from suspending?  I guess I'm just confused about the usage of "system
> suspend" in the subject line and commit message -- does "system" refer
> to the host or the endpoint?

Hi Bjorn,

System refers to the SoC which has a PCIe controller configured in 
Endpoint mode.

Thanks,
Manikanta

-- 
nvpublic